Modelling Social-Economic-Climatic Feedbacks for Policy Development

Simple models of the social-economic-climatic system offer an alternative to the standard GCM-driving scenario modelling approach, which focuses on the climate system and neglects important feedback-effects from socio-economic systems. This failure to represent the whole system is clearly problematic, because natural and socio-economic systems exhibit complex, nonlinear behaviour, and each certainly affects the other. We therefore offer an alternative approach, based on explicit modelling of the feedbacks within and between components of the system. The system dynamics simulation methodology used here facilitates representation of feedback processes, time delays, and nonlinearities, and encourages an understanding of the interconnections within a system that fundamentally determine its behaviour. As a working example of the system dynamics approach, our paper describes a simple climate-carbon cycle-water cycle-population closed-loop model. A set of three experiments compare a "business-as-usual" case with model modifications, including exogenous technology change, and endogenous equation and parameter changes. Analysis of the experimental results demonstrates model sensitivities and shortcomings: exponential growth patterns may indicate the necessity for additional model sectors and feedbacks, and sensitive relationships suggest the need for further study. Future work will improve the representation of socio-economic sectors of the model.